/*
 * Bytecode Analysis Framework
 * Copyright (C) 2003,2004 University of Maryland
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */

package edu.umd.cs.findbugs.ba;

public class ResourceValue {
    private ResourceValue() {
    }

    private static final ResourceValue instance = new ResourceValue();

    private static final ResourceValue notInstance = new ResourceValue();

    public static ResourceValue instance() {
        return instance;
    }

    public static ResourceValue notInstance() {
        return notInstance;
    }

    public static ResourceValue merge(ResourceValue a, ResourceValue b) {
        if (a == notInstance && b == notInstance) {
            return notInstance;
        } else {
            return instance;
        }
    }

    public boolean isInstance() {
        return this == instance;
    }

    @Override
    public String toString() {
        return (this == instance) ? "I" : "-";
    }
}
